Macrowine 2021

Quantification of γ-nonalactone in botrytized and non-botrytized New Zealand and Australian wines

Abstract

ƴ-Nonalactonehas been identified as a significant contributor to the aroma profile of a range of wines and is associated with stonefruit and coconut descriptors.1 The exact route ofƴ-nonalactone biosynthesis in wine has not been fully elucidated; however, precursors including linoleic acid, 13-hydroxyoctadeca-9,11-dienoic acid (13-HODE) and 9-hydroxyoctadeca-10,12-dienoic acid (9-HODE) have been identified in incubation experiments.2 Wines produced from grapes infected with “noble rot” caused by Botrytis cinerea fungus generally show higher concentrations ofƴ-nonalactone compared to non-botrytized white wines, but the relative contribution of potential formation pathways has not been elucidated.3

To assess the effect of linoleic acid on the production of g-nonalactone in wine, fermentations with and without added linoleic acid were carried out in synthetic grape must (SGM) at 28 °C using commercial Saccharomyces cerevisiae EC1118. Prior toƴ-nonalactone quantitation in the finished wines and in a subset of six Australian and New Zealand commercial wines, several routes for the synthesis of a deuterated analogue ofƴ-nonalactone were attempted, before the deuterated d6-analogue ofƴ-nonalactone from its non-deuterated analogue was produced successfully. Subsequently, attempts were made to utilise the d6-ƴ-nonalactone analogue as an internal standard for the measurement of g-nonalactone using gas chromatography-mass spectrometry. However, the synthetic d6-ƴ-nonalactone analogue proved to be an inappropriate internal standard for this purpose, due to back-exchange of deuterium atoms in wine. 2-Octanol was instead utilised as a surrogate internal standard for the measurement ofƴ-nonalactone.ƴ-Nonalactone was successfully identified (above the limit of detection, 4.12 g L-1) in two commercial New Zealand botrytized wine samples, and one fermentation sample to which linoleic acid (132 mgL-1) had been added. This suggests a possible link between the effect of Botrytis cinerea and/or linoleic acid, and increased levels ofƴ-nonalactone in wine. Further research is needed in this area to determine the mechanism ofƴ-nonalactone biosynthesis and to more accurately quantifyƴ-nonalactone in wine, using a more effective internal standard.

DOI:

Publication date: September 15, 2021

Issue: Macrowine 2021

Type: Article

Authors

Gillean Miller

School of Chemical Sciences, University of Auckland,Lisa PILKINGTON, School of Chemical Sciences, University of Auckland Bruno FEDRIZZI, School of Chemical Sciences, University of Auckland David BARKER, School of Chemical Sciences, University of Auckland Rebecca DEED, School of Chemical Sciences and School of Biological Sciences, University of Auckland

Contact the author

Keywords

 botrytized wines, botrytis cinerea, gc-ms, lactones

Citation

Related articles…

Winemaking processes discrimination by using qNMR metabolomics

AIM: Metabolomics in food science has been increasingly used over the last twenty years. Among the tools used for wine, qNMR has emerged as a powerful tool to discern wines based on environmental factors such as geographical origin, grape variety and vintage (Gougeon et al., 2019a).

Read More

The film-forming Pichia spp. in a winemaker’s toolbox: A simple isolation procedure and their performance in a mixed-culture fermentation of Vitis vinifera L. cv. Gewürztraminer must

Certain yeast species belonging to the Pichia genus are known to form a distinctive film on grape must and wine. In a mixed-culture type fermentation, Pichia spp. (P. kluyveri in particular) are known to impart beneficial oenological attributes. In this study, we report on an easy isolation method of Pichia spp. from grape must by exploiting their film-forming capacity on media containing 10% ethanol. We isolated and identified two Pichia species, namely Pichia kudriavzevii and Pichia kluyveri, and subsequently co-inoculated them with Saccharomyces cerevisiae to ferment Gewürztraminer musts. Noteworthy differences included a significant increase in the 2-phenethyl acetate levels with the P. kluyveri co-fermentation and a general increase in ethyl esters with the P. kudriavzevii co-fermentation. Both Pichia co-inoculations yielded higher levels of glycerol in the final wines. Based on all the wine parameters we tested, the P. kluyveri strain that was isolated performed similarly to a commercial P. kluyveri strain.

Read More

Exploring the influence of terroir on the sensorial and aroma profiles of wines – An application to red wines from AOC Corbières

The aromatic profile of a wine is the result of volatile molecules present in grapes (varietal or primary aromas) and those produced during the winemaking process of fermentation (secondary aromas) and during wine aging (tertiary aromas).

Read More

Free and bound terpene profile of recovered minority white grape varieties by GC × GC-TOFMS

Climate change presents a significant challenge for actual viticulture. In this context, recovering minority grape varieties can be a crucial strategy to ensure resilience, particularly those capable of maintaining quality and aromatic complexity under water stress.

Read More

Comparison between the volatile chemical profile of two different blends for PDO “Valpolicella Superiore”

Valpolicella is a famous wine producing region located in the north of Verona close to Garda lake and owes its fame above all to the production of two Protected Designation of Origins (PDOs) withered wines: Amarone and Recioto. Nowadays the production of another PDO, Valpolicella Superiore is gaining more attention by the consumers, increasing the interest of the wineries to improve the quality of this wines

Read More